Aging Brains Show Surprising Mix of Decline and Adaptation
As our bodies age, our brains age as well. But as new research examining brain function and structure shows, it’s not a clear story of decline. In fact, the brain undergoes a series of “synergistic” and “contradictory” changes that seek to counteract and compensate for structural decline.
“This supports a growing consensus that age-related brain changes are multifactorial and interconnected, rather than localized or isolated to a single modality,” the researchers write in the journal. Research explain.
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The aging brain
As we age, the brain undergoes a number of changes: neurons are lost, white matter deteriorates, and overall connectivity decreases. These patterns are closely linked to cognitive decline and help explain why functions such as memory and motor control decline as we age.
To study the aging process, researchers have typically focused on either brain function (using resting-state fMRI, which measures brain signals during a period of inactivity) or brain structure (using sMRI, which takes detailed images of brain anatomy). In a new study, scientists from Shanxi University in China and Georgia State University in the United States combined the two to create a more complete picture of the aging process.
The team first examined the predictive abilities of brain function (measured by functional brain network connectivity) and brain structure (measured by gray matter volume) separately, then assessed the predictive abilities of the two jointly. This was followed by an analysis focusing on aging patterns.
“This design allows us to offer a more nuanced and integrative understanding of the neurobiological aging process,” the study authors wrote.
Predict Chronological Age
The research was carried out using data collected by the UK Biobank, a large database containing health, biological and lifestyle information on around half a million people. In total, more than 27,500 healthy middle-aged and older adults (49 to 76 years) were included in the study.
The researchers accurately predicted participants’ chronological age from brain function and structure, but models comparing gray matter volume were more accurate than those analyzing brain connectivity. This, they say, suggests that age-related structural changes may be more pronounced than age-related functional changes – a finding they emphasize is “consistent with existing knowledge.”
Yet examining structure and function together proved to be the most effective method of all and outperformed models that examined only one of the two.
“Synergistic” and “contradictory” changes
A closer look at the patterns associated with aging revealed a complex combination of “synergistic” and “contradictory” changes.
Aging was correlated with decreased functional brain network connectivity and gray matter volume in the cerebellum, frontal pole, paracingulate gyrus, and precuneus cortex – areas of the brain associated with motor control, sensory processing, emotional regulation, and higher-order cognition. The researchers described these as “synergistic” changes.
However, in other brain regions, gray matter shrinkage was accompanied by an increase in functional brain network connectivity – a “contradictory” change that suggests the body compensates for structural decline by improving connectivity, helping to retain cognitive abilities and behavioral control as a person ages.
These “contradictory” changes were most notable in the occipital pole and lateral occipital cortex, areas associated with visual functions, fluid intelligence and numerical processing.
“These findings collectively highlight that brain aging is not a unidirectional degenerative process but rather involves dynamic adjustments and reconfigurations across specific networks and hemispheres, aimed at preserving functional stability and cognitive capacity for as long as possible,” the study authors explained.
“This contributes to ongoing efforts in the fields of aging and cognitive neuroscience to advance more personalized and preventative approaches to brain health monitoring,” the authors concluded.
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